Content aware image retargeting is related to image processing in which an image is resized according to its content. The image size is changed without removing pixels of the image (as opposed to image cropping) or without distorting the relevant content (as opposed to image scaling wherein the pixel size is reduced).
In Seam carving for content-aware image resizing (Avidan and Shamir, in proceeding of SIGGRAPH '07 ACM SIGGRAPH 2007, Article No. 10) vertical and horizontal lines of adjacent pixels are removed from the image thus reducing the size of the image. Augmentation in the image size is done by adding lines of adjacent pixels. The computation of an image significance cost is carried out in order to drive the algorithm and to tell the algorithm which line of adjacent pixels to remove.
However, seam carving may produce artifacts in the image since when a vertical line is removed only one pixel per row in the image is removed. This removal creates discontinuities in the image that are characteristic of this kind of method.
The removal of one or a group of pixels at once characterizes Discrete transformation methods. However, these Discrete transformation methods all suffer from the same flaw; they generate serious artifacts due to the discontinuities generated by the removal or the aggregation of pixels that were not contiguous in the first place.
Discrete transformation methods are opposed to Continuous transformation methods in which a continuous mathematical function assigns new positions to the pixels, and since the positions are not always integral positions while the positions of pixels in an image represented inside the memory of a computer is always an integer, interpolation (linear, quadratic . . . ) is required to recover the image. The known Continuous transformation methods generally deal with a continuous transformation that is applied to the image through interpolation.
However these transformations are merely an affine shrinkage inside cells that are defined on the image, and as such, the transformation is only piecewise smooth across the image which can also create artifacts, especially on the edges of the cells. These methods also need an explicit account for fold overs, namely when the transformation gets wrapped around itself and pixels are simply disappearing from the image resulting in displeasing visual results.
Within this context, there is still a need for an improved method for resizing an image.